Today, off-highway trucks, in particular off-highway trucks having carrying capacities of four-hundred (400) tons or more, are used in a number of off-road environments for hauling a variety of materials. As the generic name implies, these vehicles are limited to off-highway and/or private road use and are commonly used in a mining environment. Typically, these off-highway vehicles operate on unpaved gravel/aggregate roads.
In mining operations, fleets of off-highway trucks approach fifty (50) to one hundred (100) off-highway trucks, with these off-highway trucks often operating twenty-four (24) hours a day, three hundred sixty (360) plus days a year. Operating around the clock, environmental conditions can be challenging and it is not unusual for an off-highway truck or vehicle to occasionally become disabled.
Because of the sheer size and weight of such off-highway trucks or vehicles (often approaching hundreds of thousands of pounds and often standing over twenty (20) feet high) the task of recovering and/or retrieving such a disabled off-highway truck or vehicle and moving it to a repair facility can be unique and challenging. Typical sizes of off-highway trucks used in mining environments, etc denoted by their payload classes, gross loaded vehicle weights, and empty weights are;                1. 50 Ton Class Payload                    Gross Laden Weight 200,000 lbs/Empty Weight 80,000 lbs.                        2. 100 Ton Class Payload                    Gross Laden Weight 400,000 lbs/Empty Weight 160,000 lbs.                        3. 150 Ton Class Payload                    Gross Laden Weight 550,000 lbs/Empty Weight 240,000 lbs.                        4. 200 Ton Class Payload                    Gross Laden Weight 715,000 lbs/Empty Weight 320,000 lbs.                        5. 250 Ton Class Payload                    Gross Laden Weight 850,000 lbs/Empty Weight 360,000 lbs.                        6. 300 Ton Class Payload                    Gross Laden Weight 1,000,000 lbs/Empty Weight 440,000 lbs.                        7. 350 Ton Class Payload                    Gross Laden Weight 1,260,000 lbs Empty Weight 560,000 lbs.                        8. 400 Ton Class Payload                    Gross Laden Weight 1,380,000 lbs/Empty Weight 610,000 lbs.In each of these classes different brands of off-highway trucks will have plus/minus payload tonnage, gross laden weight, and empty weight variations.                        
Off-highway trucks in particular are one of the most prevalent mobile vehicles on a typical mine site. By way of reference, 90 to 95% availability of a mine off-highway truck fleet is considered excellent availability, with 5% to 10% of the off-highway truck fleet being unavailable or disabled at any time. Accordingly, in a fleet of fifty (50) off-highway trucks, at any given time five (5) trucks could be disabled and in need of repairs. Of course, these numbers vary from mine to mine and are somewhat dependent on the age of the off-highway truck fleet as well as the particular severity of the mining operation (steep haul road grades, poor environmental conditions, availability of good service technicians, etc.).
But if one were to assume that there might be five (5) disabled off-highway trucks at any one time, it would be fair enough to consider that at least two (2) or three (3) of these off-highway trucks could have become disabled at some distance from the off-highway truck maintenance and repair facility.
The typical way to move disabled off-highway trucks is to either tow them with chains or cables or pick them up by the front bumper to get the off-highway truck's front tires off the ground and then pull on the front bumper to move the off-highway truck. The front bumper o typical off-highway trucks is strong enough to sustain this lifting and pulling effort, though in some cases the front bumpers are reinforced. And, reinforced replacement front bumpers specifically designed for lifting and towing disabled vehicles can be purchased from Weldco-Beales of Edmonton, Alberta. To understand the forces required to lift the front of such an off-highway truck, consider a two hundred filly (250) ton capacity off-highway truck. The ‘empty’ weight of such an off-highway truck is plus/minus about two hundred fifty thousand (250,000) pounds. The vertical force required to lift the front of an empty off-highway truck from the front bumper can be about ninety thousand (90,000) pounds, while in the ‘loaded’ condition this off-highway truck can weigh about eight hundred fifty thousand (850,000) pounds. The front bumper lifting force required to lift this loaded off-highway truck can be about one hundred eighty thousand (180,000) pounds.
In some mines, it is typical to use a dedicated off-highway truck towing chassis with an incorporated lifting hook extending rearward from the off-highway truck towing chassis to hook on and lift/pull disabled off-highway vehicles. The rearward extended lifting hook must extend far enough behind the rear tires of the off-highway truck towing chassis so that as the off-highway truck towing chassis turns, the rear tires of the off-highway truck towing chassis do not come in contact with the front of the towed disabled vehicle. This off-highway truck towing chassis rearward extending lifting arrangement requires an off-highway truck towing chassis that is heavy enough to counterbalance the load imparted on the lifting hook when one end (e.g., the front end) of a disabled vehicle is picked up. Accordingly, it is often necessary to counterweight the front bumper of the off-highway truck towing chassis. Consequently, when not towing a disabled vehicle, the front axle of an off-highway truck towing chassis is often near overload or overloaded. Also, when the off-highway truck towing chassis has lifted and is towing a disabled vehicle, the rear axle of such an off-highway truck towing chassis is carrying an extreme load and may be overloaded.
Accordingly there are disadvantages associated with the conventional off-highway truck towing chassis rearward extending lifting/towing hook. One major disadvantage is the rear axle loading of the off-highway truck towing chassis that occurs when towing a disabled vehicle. The entire load being picked up and towed is being carried on the off-highway truck towing chassis rear axle. The off-highway truck towing chassis rear axle loading is similar to the center support load of a teeter-totter. Another significant disadvantage is that a front bumper counter balance weight is normally required on the off-highway truck towing chassis. These two factors severely impact the off-highway truck towing chassis, i.e., the rear axle loading when towing a disabled vehicle and the counterbalance front axle load weight when not towing a vehicle, and often result in extreme wear on the off-highway truck towing chassis at the front and rear chassis axles. Another drawback is the mechanical disadvantage at which the towing/lifting arrangement operates. When operating from the rear of the off-highway truck towing chassis, the size of the hydraulic cylinders and hydraulic oil flow required to raise and lower this lifting/towing hook is large. A further issue is the inability to easily move the lifting/towing hook side to side as the lifting/towing hook aligns with a companion socket on the disabled vehicle's bumper. An additional drawback to this lifting/towing arrangement is the sheer structural size required to operate at a considerable distance behind the rear tires of the off-highway truck towing chassis. Another complication of the rearward extending lifting/towing arrangement is the mechanical disadvantage in which an off-highway truck towing chassis rearward extending lifting/towing arrangement operates, i.e., only empty off-highway vehicles can easily be lifted and towed.
As such a need has developed to provide a superior hitting/towing arrangement for all sizes of off-highway vehicles and in particular off-highway trucks whether empty or loaded. The need is for an improved lifting/towing arrangement that has better flexibility and function, permitting the lifting/towing arrangement to be multi-functional. In addition, an improved lifting/towing arrangement will allow for increased hauling capabilities when used in a lowboy trailer towing configuration. There is also a need for an improved lifting/towing function that will allow for the use of Prime Movers several truck classes smaller (the off-highway truck towing chassis) to lift and tow larger loads. For example a 100 ton class off-highway truck can 200 ton class off-highway truck, a 150 ton class off-highway truck can tow a 300 ton class off-highway truck, and a 200 ton class off-highway truck can tow a 400 ton class off-highway truck.